Spring hammer



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Jan. 12, 1954 i lNvENToR Z". 291,1an/:11u911 ATTORNEY Patented Jan. l2, 1954 SPRING HAMMER gnaz `Pix-knel', Graz-Andritz, Austria, assgnor o! one-half to Maschinenfabrik Andritz Aktiengesellschaft, Graz-Andritz, Austria, a rm o! Austria Application July 7, 1949, Serial No. 103,495

Claims priority, application Austria July 10, .1948

(Cl. 7S-32) 14 Claims.

The present invention relates to improvements in power hammers Vof the type known as spring hammers.

In contradistinction to other hammers it has hitherto in general only been possible to use spring hammers for those operations, in which a series of blows were to be delivered in continuous .succession. For driving a spring hammer relatively heavy gyratory masses are required, which have to be braked each time the hammer is brought to rest and be put in motion again at each restarting of the hammer. 'In view of this expenditure of energy the delivery of single strokes was irrational and the hammer driven .by the gyratory masses was diicu'lt to control.

Now, the present invention has for its object to overcome these 'disadvantages and to provide a .spring-controlled hammer suitable for general use. The invention consists substantially in this, that in a spring hammer having a driving mech anism formed by a crank or an eccentric the driving mechanism is connected with the rotating gyratory masses through a releasable coupling and that preferably the masses which are in constant connection with the hammer head are also reduced by substituting for the balancing weights for the hammer head, balancing mem bers of slight mass, such as springs, compressed air pistons and the like.

'Through the construction according to the `invention such a spring hammer is given new prop erties which modify its mode of operation and open up new uses for it. The 'hammer is capable of being brought to rest at any moment, without the necessity of braking the gyratory masses which `may continue to rotate with `the driving parts, so that, on starting to work again, the full energy ofthe gyratory masses Vfor operating the hammer is available. Through the further expedient of replacing the normally provided balancing weights'for the hammer head by massless balancing lmember or members, thev mass of which is negligible, it becomes possible, to also reduce the kmasses of the hammer, which `have each time to be brought to rest and vprut in motion. Throughthis extensive balancing of the hammer head masses the :coupling isstressed uniformly and it becomes possible with such `a mechanical vspring hammer to deliver .the lightest strokes. According to the invention an effective brake is provided, =by means of which it is possible, on the fgyratory masses being put out of action, to hold l'the 'hammer head -in any position.

".lhus, whilst hitherto, on starting up the haine mer, :great masses 'had to 'be accelerated, so that the full strength and rate `of blows could be only gradually reached with a great expenditure or energy, the invention enables the blows to start immediately at full speed and full strength. .Hitherto it has also only been possible to stop the .hammer gradually, whereas the invention en-.- ables the hammer to be brought to rest suddenly. Owing to the circumstance, that the energy stored inthe gyratory masses is :conserved and not lost.. it becomes possible to vselect less powerful and more economical driving motors.

The invention provides the very important ad-f vantage, that the possibility of suddenly karresting the hammer in any desired position renders it capable of delivering sitting blows. For bring.- ing the hammer to rest in the blow-.delivering position with the laminated spring in the stressed state, the procedure may be such that it presses the work on the anvil and holds it under the pressure of the laminated spring. According `to the invention this is Veffected through the brake which, for increasing its eiectiveness, may be `constructed as a band brake or multi-shoe brake mounted on the driving mechanism or on the crankshaft of the hammer. This brake may, ac cording to the invention, be relieved of pressure by means which prevents a backward motion of the driving mechanism, more particularly a clutch arrangement.

The coupling and the brake may be operated at will or automatically, Preferably a control .is provided, which puts the gyratory masses out 0f action, that is uncouples the coupling, and puts the brake into operation. According to the invention the actuation of this control may be automatic in dependence on the position of the hammer or on the position of the crankshaft. .In this case,.for instance, .the .crankshaft is provided with a cam disc, from which the control is derived.

The invention thus enables the mechanical spring hammer with `crank or eccentric drive to be used both as heretofore in the usual way for a succession .of blows and for single blows, more particularly for sitting blows, and the control of the hammer to be made considerably more sensitive than in the constructions 'hitherto used. Hitherto vonly pneumatic orsteam hammers have been suitable for work requiring single blows. It has already been proposed to drive ,spring `ham-- mers vby means of a compressed air piston applied to the laminated spring, the arrangement being such that the drive .could be interrupted by valve control. Reversing .spring hammers, in which the laminated spring is kalternately coupled with puls leys rotating in opposite directions, are also known. Both types, however, necessitate a complicated construction and neither comprises rotating parts which are permanently connected with the hammer head and on which an effective brake for bringing the hammer to rest can be provided. 'c

The invention is illustrated diagrammatically by Way of example in the accompanying drawing, in which:

Fig. 1 shows the hammer in side elevation and Fig. 2 a vertical section in the plane of the driving crankshaft;

Figs. 3 and 4 show details of the construction of the cam disc intended for the automatic control and of a clutch arrangement;

Fig. 5 is a diagrammatic planview illustrating how the control is operated.

In a hammer frame I with two bearings 2 runs the crank or eccentric shaft 3, on the driving end of which is mounteda coupling or clutching disc 4 that can slide along a key 5. A brake pulley 6 is rigidly keyed to the other end of shaft 3. The cranked portion of crank shaft 3 carries the connecting rod 1, the connecting rod head 8 of which is connected to and moves the laminated spring I which is supported in two bearings 9 on the frame. This movement moves the hammer head I I up and down in vertical guides provided in the frame I so as to strike the forging or other work I3 resting on the anvil I2. The hammer is driven from the driving fly Wheel I which runs freely on ball bearings i4 at the outer end of the crankshaft 3. One side of the flywheel is constructed as part of a cone coupling or clutch. By moving the coupling disc 4 into engagement with the continuously rotating driving fly wheel I5 the hammer is put in operation and, by withdrawing it to disengaged position the hammer is put out of operation. As shown in the drawing, the flywheel I5 has mass characteristics such as to impart a sudden and powerful stroke to the connecting rod and thus a sudden and powerful blow to the hammer head when the clutch is engaged.

The result of this arrangement is, that the ,y

inner non-uniformly running driving part of the spring hammer is entirely freed from gyratory masses, as the latter are disconnectable outside the hammer drive proper. In contradistinction to the known construction these gyratory masses may romani in continuous rotation. The weight masses for balancing the hammer head are also eliminated and replaced by a spring I6 which is interconnected between the laminated spring I0 and the frame. hereinbefore indicated, resilient compensating means for counteracting the weight of a hammer head and in the illustrated embodiment, it is concted to the leaf spring between the pivoting axis of the laminated spring and the connecting rod. The spring may equally well be attached at the end of the laminated spring, at the horizontal axis formed by the pivot pin or at any other point. The hammer head is shown in the stopped sitting position and the laminated spring IB in the tensioned position. In this position the laminated spring I0 exerts during the blow and after the blow an additional pressure on the forging. For taking up the spring tension a band brake II, in the form of invention illustrated, is provided. The brake pulley or drum 6 has a cast-on lateral rim I8 for coacting with a clutch arrangement, Fig. 4, or some other form of motion-arresting device. This clutch arrangement which may.v for m- This spring I3 constitutes, as

stance, also be constructed as a roller clutch device prevents the connecting rod I from turning back both after the crankshaft has been brought to rest and on the brake being released, whereby the energies stored in the stressed laminated spring I0 and in the stressed balancing springs I6 remain conserved for the next blow of the hammer. The clutch arrangement i according to Fig. 4, which consists of the strap I9, an outer shoe 20 and an inner shoe 2 I, which parts are connected by the bell crank 22 and are pressed by a spring 23 against opposite sides of the rim I8 of the brake pulley, permits the brake pulley and consequently the crankshaft to turn only in the direction of the arrow. Therefore, it is clear that the clutching device of Figure 4 is in effect a one way self-energizing brake. In other words, there is no operating mechanism necessary to cause the shoes 20 and 2| to grip the rim I8 since the manner of supporting the same and the particular vstructure illustrated in Figure 4 provides rthat the rim I3 may rotate in one direction but any attempt to impart reverse rotation to this rim will be prevented by an automatic increase of the friction between the shoes.

and the rim. The structure is such that the friction or braking pressure is greater if the force tending to reversely rotate the rim I8 increases. This structure, therefore, constitutes a self-energizing brake mechanism.

With the spring hammer according to the invention sitting blows which can be delivered singly or in succession, may also be made to function automatically, as shown by way of example in Figs. 2 and 3. On the side facing the crankshaft bearing the coupling disc 4 is formed as a cam disc 24, on which runs the roller 25 at one end of the bell crank 2B. At the upper end of the bell crank 26 is pivotally attached the pull-back latch member 28 which rests on a lug 2T of the lever 26. Now, by depressing the foot lever 29 the feed shaft 32 is turned by way of the shaft 30 and the bevel wheels 3 I, Fig. 5, and two rocking levers 33 connected to shaft 30 throw the coupling disc 4 into engagement. In the starting position the roller 25 is always on the swell of the cam disc 24 and the pull-back latch member 28 is out of engagement in the ready position, so that, as will be seen from the drawing, the connecting rod 34 of the two rocking levers 33 can, on the coupling disc 4 being brought into engagement, be moved along below the pull-back latch member 28.

As the coupled crankshaft 3 and the cam disc 24 continue rotation, the roller 25 on the bell crank 26 moves downwards on the descending portion of the cam and, by displacing the pullback latch member 28 and lowering the lug 21, causes the former to engage with the connecting rod 34. On the roller 25 ascending the next cam swell, the bell crank by means of the pull-back latch member 28 pulls the two rocking levers 33 back and puts the coupling and the direct hammer drive out of operation. At the same time the brake band I1 is tensioned through the connecting rodwork by the action of weight 35 and the hammer brought to rest during its stroke.

At the end of its pull-back motion the latch member 28 is again lifted by the lug 21 of-the bell-crank 2S o the connecting rod 34 and brought into the ready position. Any play in the power transmission of the coupling rodwork will be eliminated by the spring 36. Through this arrangement the hammer is brought to rest after ealjrdepressioniof the vfoot lever aftereach. stroke 5 in its predetermined position, whilst the brake clutch according to Fig. 4 prevents the crank 3 from turning back under the iniiuence of the .tensioned laminated spring I0. AIn this Way the energy given off by the hammer head Il is additionally assisted by the pressure ofthe tensioned laminated. spring for obtaining an increased effect of the sitting stroke. As, however, gyratory masses rotating at the full speed of revolution are at all times available, the single stroke can be delivered with far greater power and far more rapidly than has hitherto -beenpossibla The elimination of all sudden loads on the driving lmotor also makes the usegof weaker motors possible.

AWhat I claim is:

l. A spring hammer including a frame, a laminated spring swingably mounted on said frame, a hammer head attached to one end of said laminated spring, a connectingrod attached to the opposite end of said spring, a crank shaft rotatably J'ournalled in said-frame and including a crank portion operably connected to said connecting rod, driving means for rotating said shaft including a fly wheel adapted for continuous rotation, clutch means for detachably coupling the crank shaft to said fly wheel, said flywheel having such mass characteristics as sufficient to impart a sudden and powerfu1 stroke to the hammer head when the clutch means is engaged, brake I meansfor stopping the rotation of the crank shaft and thereby stopping the hammer when said clutch means is disengaged and resilient compensating means counter-acting the weight of the hammer head, l2. A spring hammer including a frame, a laminated spring swingably mounted on said frame, a hammer head attached'to oney end of said laminated spring,'a connecting 'rod attached to the opposite end of said spring, a crank shaftrotatably journalled in said frame and including a crank portion operably connected to said connecting rod, driving means for rotating said shaft including a ily whee1 adapted for continuous rotation, clutch means for detachably coupling the crank shaft to said fly wheel, said ny wheel having such mass characteristics as to impart a 'sudden and powerful stroke to the connecting rod and thus to the hammer head when the clutch means isengaged, brake means for stopping the rotation of the crank shaft and thereby stopping the hammer when said clutch means is disengaged, a one way clutching means operably associated with the crank shaft for preventing reverse rotation thereof when said first-mentioned clutch is disengaged and resilient compensating means counter-acting the weight of the hammer head.

3. A spring hammer as deiined in and by claim 2 in which said second-mentioned one way clutch means comprises a self-energizing brake mechanism.

4. A spring hammer including a frame, a laminated spring swingably mounted on said frame, a hammer head attached to one end of said laminated spring, a connecting rod attached to the opposite end of said spring, a crank shaft rotatably journalled in said frame and including a crank portion operably connected to said connecting rod, driving means for rotating said shaft including a fly whee1 adapted for continuous rotation on said crank shaft, clutch means for detachably coupling the crank shaft to said ily wheel, said ny wheel having suchl mass characteristics as suicient to impart av sudden and powerful stroke to the connecting rod and thus to the hammer head when the clutch means is engaged, brake means for stopping the rotation of the crank shaft and thereby stopping the hammer when said clutch means is disengaged, resilient compensating means counteracting the weight of the hammer head, said brake means including a brake drum keyed to said crank shaft, a brake band cooperable with said drum and means for tensioning said band to apply the brake, said drum having a lateral rim, separate self-energizing one way brake means supported by the frame and including pivotally mounted friction shoes engaging opposite surfaces of said rim and operative to permit rotation of said brake drum in one direction but to prevent reverse rotation thereof under influence of said laminated spring.

5. A spring hammer as defined in and by claim 1 in which the resilient compensating means comprises a spring and said spring being connected at one end to said frame and at its other end to said laminated spring for counter-acting the weight of the hammer head.

6. A spring hammer as dened in and by claim 1 and means for releasing the clutch and operat- 7. A spring hammer as defined in and by claim 6 in which the clutch means includes a clutching member axially slideable to clutch engaged and disengaged positions, respectively, and swingable rods for sliding said member and in which the means for automatically releasing the clutch and operating the brake in dependence on the operative position of the crank shaft includes a bell said cam follower and a pull-back latch member pivotally mounted to the opposite end of said bell crank and cooperating with said pivoted rods for effecting clutch disengaging sliding movement of the rods.

8. A spring hammer as defined in and by claim '7 and abutment means carried by said bell crank and engageable with said pull-back latch member for disassociating the same from said rods prior to the pull-back latch member reaching its rest position.

9; A spring hammer as defined in and by claim l inwhich the clutch means includes control members and a clutching member and pressure means acting on the clutching member to eliminate play between the control members and the clutching member.

10. A spring hammer including a frame, a laminated spring pivotally mounted in said frame for swinging movement about a horizontal axis, a hammer head connected to one end of said laminated spring,'a connecting rod connected'to the other end of said spring, guide means on said frame for constraining the hammer head to reciprocating movement, drive means for reciprocating the hammer head including a crank shaft journalled in said frame having a cranked portion operably connected to said connecting rod, the axis of rotation of said crank shaft being parallel with the axis of pivotation of said lami-1 nated spring, a brake drum keyed to one end of said crank shaft, a fly wheel adapted for constant rotation rotatably mounted on the opposite end of said crank shaft and positioned exteriorly of said frame, clutch means including` a clutching member keyed to said crank shaft between the frame and the dy wheel for axial sliding movement, respective clutch surfaces on said member and said fly wheel whereby said fly wheel cooperates with the clutching member to provide a coupling to rotate the crank shaft, control rods pivotally mounted to said frame for moving said clutching member, movable means for pivoting said rods to engage and disengage said coupling, said y wheel having such mass characteristics as sufficient to impart a sudden and powerful blow to the hammer head when the coupling is engaged, a brake band associated with said brake drum and means for tensioning said band when said clutching member is moving to disengaged position and a one way selfenergizing brake means associated with said brake drum and automatically operable to permit rotation thereof in one direction, but to prevent rotation thereof in the reverse direction upon disengaging said clutching member and a spring inter-connected between said laminated spring and said frame for resiliently compensating for the weight of the hammer head, said last mentioned spring being connected to the leaf spring between said horizontal axis and the connecting rod.

11. A driving and control mechanism for a spring hammer comprising a connecting rod for imparting reciprocatory movement to the hammer, a rotatably mounted crank shaft including a cranked portion operably connected to the connecting rod, a continuously rotatable fly wheel, clutch me'ans for detachably coupling the crank shaft to said fly wheel and said fly wheel having such mass characteristics as to impart a sudden and powerful stroke to said connecting rod when the clutch is engaged, controllable brake means for stopping the rotation of the crank shaft and thereby movement of the connecting rod when the clutch means is disengaged, resilient compensating means counteracting the Weight of the hammer head and a one-way clutching mechanism oper-ably associated with the crank shaft for preventing reverse rotation thereof when the first mentioned clutch means is disengaged and upon release of said brake means.

12. A driving and control mechanism for a spring hammer of the type including a hammer head reciprocably mounted in a frame, said driving mechanism including a connecting rod for imparting reciprocatory movement to the hammer, a crank shaft rotatably journalled in the frame and including a cranked portion operably connected to the connecting rod, said crank shaft including portions projecting beyond each side of the frame, a fly Wheel rotatably jornalled on the projecting portion at one side of the frame, a clutch mechanism movably mounted on said crank shaft between the fly wheel and the frame and movable between clutch engaged and disengaged positions and cooperable with the fly wheel for detachably clutching the same to the crank shaft to impart rotation to the crank shaft when engaged for operating the hammer, said fly wheel having such mass characteristics as to impart a powerful stroke to the connecting rod when the clutch means is engaged, a brake drum keyed to the other projecting portion of said shaft at the opposite side of the frame, a brake band cooperable with said drum and means for releasably tensioning said band to brake the crank shaft for stopping the stroke of the connecting rod when said clutch means is disengaged, said brake drum having a lateral rim, a separate self-energizing brake means supported by the frame including pivn otally mounted friction shoes engaging opposite sides of said rim and operative to permit rotation of said brake drum in one direction but to prevent reverse rotation thereof in an opposite direction when said tensioning means are released and resilient compensating means for counteracting the weight of the hammer head.

13. A driving and control mechanism for a spring hammer as dened in and by claim 11 and further including means for disengaging the clutch and operating the brake means in clependence upon the operative position of the crank shaft.

14. In a driving mechanism for a spring hammer, a rotatably mounted crank shaft, a connecting rod operable by said crank shaft for imparting a stroke to the hammer, a continuously rotatable ily wheel journalled on said crank shaft, clutch mechanism mounted on the crank shaft and operable to. detachably couple the crank shaft with said fly Wheel so that the' Iiy Wheel imparts rotation to the crank shaft, brake means mounted on the crank shaft for stopping the rotation thereof when the clutch means is disengaged, means for preventing reverse rotation of the crank shaft when said rst mentioned clutch means is disengaged and resilient compensating means for counteracting the weight of the hammer head.

PIRKNER, IGNAZ.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 816,291 Blackstone Mar. 27, 1906 837,519 Tolley Dec. 4, 1906 941,093 Painter Nov. 23, 1909 953,768 Sutherland Apr. 5, 1910 977,082 Embry Nov. 29, 1910 1,646,932 Rosenberg Oct. 25, 1927 FOREIGN PATENTS Number Country Date 39,943 Austria June l, 1909 

